Studies designed to assess the histomorphological, ultrastructural histochemical and biochemical characteristics of altered cell types in pulmonary neoplasms of mice have been done. Over the past three years, we have evaluated the gross, histomorphological and ultrastructural features of pulmonary neoplasms in aged Strain A mice, B6C3F1 mice and also F344 rats using conventional light and electron microscopy. Automated lectin staining and two dimensional gel electrophoresis have been used to characterize the glycoconjugate composition of nonneoplastic versus neoplastic cells, and malignant versus benign neoplasms in Strain A mice. Studies designed to evaluate the interaction of fibers and chemical carcinogens on pulmonary tumorigenesis are underway.